1. Field of the Invention
The present invention relates to a printing apparatus. More particularly, the invention relates to a printing apparatus which performs print registration upon bi-directional printing in which printing is performed during a forward scan and a reverse scan of a printing head or upon printing employing a plurality of printing heads.
2. Description of the Prior Art
Conventionally, printing registration of this kind is generally performed in the following manner.
For example, in the case of printing registration for the bi-directional printing where a forward scan and a reverse scan are performed to perform printing, a relative printing registration condition for the respective forward and reverse scans is varied by adjusting respective printing timing in the forward scan and the reverse scan and ruled lines are printed on a printing medium during the respective forward and reverse scans with use of the respective printing registration conditions. Then, a result of printing is observed by a user or the like to select the printing registration condition where best printing registration is achieved and a printing condition concerning the printing registration is set in a printing apparatus, a host computer or the like.
In the case of the printing registration between heads in the printing apparatus in which a plurality of printing heads are employed for printing, the ruled lines are printed by respective heads with varying the relative printing registration condition between the heads. Then, the printing registration condition where the best printing registration is attained is selected, by the user or the like, similarly to the above, to set the selected printing registration condition in the printing apparatus, the host computer or the like.
However, such conventional printing registration methods are accompanied by a troublesome operation that the user or the like observes a print result for the printing registration to select the printing registration condition and performs an operation for setting the printing registration condition. Therefor, some users, for whom such troublesome operation is unfavorable, may not perform the printing registration and use a printing apparatus in a condition containing a disagreement of printing positions between the respective forward and reverse scans or a disagreement of printing positions between the respective heads.
Furthermore, in the conventional methods, the printing registration condition can be selected only among respective printing registration conditions represented by printed patterns for the printing registration. For further printing registration with higher precision, it becomes necessary to perform printing of greater number of patterns with slightly varying the printing registration condition and it is also necessary for the user to distinguish delicate difference among the printed patterns to select the printing registration condition. In addition to trouble of the user, it takes a long period for performing the printing registration and require large number of patterns printed on the printing medium.